Bone screw removal system

ABSTRACT

A bone screw removal system for a bone screw retaining system that includes an implant having a plate, which defines a plurality of transversely extending bores that are configured to receive a bone screw for engaging the plate to the cervical spine, and an elastically deformable spring member positioned therein a cavity of the plate such that portions of the spring member can extend into a portion of an upper region of each of the bores of a pair of opposing bores, the spring member being movable between a first relaxed, expanded position and a second, compressed position. The bone screw removal system having at least one tongue member that is configured to selectively act on the spring member of the bone screw retaining system.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of U.S. ProvisionalApplication No. 60/821,456, filed Aug. 4, 2006, which is incorporated inits entirety in this document by reference.

FIELD OF THE INVENTION

The present invention relates generally to surgical procedures, mostparticularly for use in fixation of the cervical spine. Moreparticularly, the invention pertains to a bone screw removal system foruse in removing screws from a plate system, such as, for example, thosefor use in anteriorly fixating adjacent cervical vertebrae.

BACKGROUND OF THE INVENTION

As with any bony structure, the spine is subject to various pathologiesthat compromise its load bearing and support capabilities. The spine issubject to degenerative diseases, the effects of tumors and, of course,fractures and dislocations attributable to physical trauma. In the past,spinal surgeons have tackled the thorny problems associated withaddressing and correcting these pathologies using a wide variety ofinstrumentation and a broad range of surgical techniques. For example,in spinal surgeries, the fusion of two or more vertebral bodies isrequired to secure a portion of the spinal column in a desired position.Alternatively, the use of elongated rigid plates has been helpful in thestabilization and fixation of the lower spine, most particularly thethoracic and lumbar spine.

The cervical spine can be approached either anteriorly or posteriorly,depending upon the spinal disorder or pathology to be treated. Many ofthe well known surgical exposure and fusion techniques of the cervicalspine are described in Spinal Instrumentation, edited by Drs. Howard Anand Jerome Cotler. This text also describes instrumentation that hasbeen developed in recent years for application to the cervical spine,most frequently from an anterior approach.

The anterior approach to achieving fusion of the cervical spine hasbecome the most popular approach. During the early years of cervicalspine fusion, the fusions were preformed without internalinstrumentation, relying instead upon external corrective measures suchas prolonged recumbent traction, the use of halo devices or minervacasts, or other external stabilization. However, with the advent of theelongated plate customized for use in the cervical spine, platingsystems have become the desired internal stabilization device whenperforming stabilization operations.

It has been found that many plate designs allow for a uni-corticaly orbi-corticaly intrinsically stable implant. It has also been found thatfixation plates can be useful in stabilizing the upper or lower cervicalspine in traumatic, degenerative, tumorous or infectious processes.Moreover, these plates provide the additional benefit of allowingsimultaneous neural decompression with immediate stability.

During the many years of development of cervical plating systems,particularly for the anterior approach, various needs for such a systemhave been recognized. For instance, the screws used to connect the plateto the vertebrae must not loosen over time or back out from the plate.This requirement, that the bone screws do not loosen over time or backout from the plated, tends to complicate implantation of known platingsystems. Such bone screw retention systems generally ensure that thebone screws placed into the vertebrae through the plating system do notback out voluntarily from the plate, but typically do not adequatelypermit the removal of an associated bone screw when desired by thesurgeon.

It remains desirable in the pertinent art to provide a bone screwremoval system for use with a plating system that addresses thelimitations associated with known systems, including but not limited tothose limitations discussed above.

SUMMARY

In one embodiment of the present invention, a bone screw removal systemcomprises a driver assembly that is configured to drive bone screws usedto fixate a plate system having a bone screw retention system and isfurther configured to remove screws therefrom the plate system.

Related methods of operation are also provided. Other systems, methods,features, and advantages of the bone screw removal system will be orbecome apparent to one with skill in the art upon examination of thefollowing figures and detailed description. It is intended that all suchadditional systems, methods, features, and advantages be included withinthis description, be within the scope of the bone screw removal system,and be protected by the accompanying claims.

DETAILED DESCRIPTION OF THE FIGURES

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate certain aspects of the instantinvention and together with the description, serve to explain, withoutlimitation, the principles of the invention.

FIG. 1 is a top plan view of an exemplary bone screw retention systemcomprising a plate having a plurality of bores therein and a pluralityof spring members shown in a locking position with a plurality of seatedbone screws.

FIG. 2 is a perspective view of the bone screw retention system of FIG.1, showing a plurality of bone screws seated therein the bores of theplate and positioned at desired angles relative to the plate.

FIG. 3 is a perspective view of the plate of the bone screw retentionsystem of FIG. 1, showing a spring member comprising a split-ringoperable mounted in a spring mount such that, in a first relaxedposition, a portion of the split-ring extends over a portion of theupper region of the bore.

FIG. 4A is a perspective view of a bone screw being initially placedtherein the bore of the plate.

FIG. 4B is a perspective view of the bone screw being advanced into theunderlying bone, showing the spring member being deflected medially bythe taper of the head of the bone screw which allows it to pass by thespring member.

FIG. 4C is a perspective view of the bone screw as it is advancessufficiently past the spring member such that the spring member biasesback to its original relaxed position in which at least a portion is aperspective view of a bone screw being initially placed therein the boreof the plate of the spring member overlies a portion of the nowunderlying bone screw.

FIG. 5 is a partial cross-sectional view of an alternative embodiment ofthe bone screw retention system showing a plurality of spring membersmounted therein the upper portion of each bore of the plate; each springmember comprising a spring assembly that comprises a movable pistonmember biased by a coil spring.

FIG. 6 is a partial top plan view of the bone screw retention system ofFIG. 5.

FIG. 7 is a partial cross-sectional view of an alternative embodiment ofthe bone screw retention system showing at least one spring membermounted therein the upper portion of each bore of the plate; each springmember comprising an arcuate spring member mounted therein the wall ofthe upper region of the bore and which is shown in its first, relaxedposition.

FIG. 8 is a partial top plan view of the bone screw retention system ofFIG. 7.

FIG. 9 is a partial perspective view of a screw removal assembly shownin a first position in which a distal end portion of a bone screw drivemember is positioned within, and at least partially enclosed by, thedistal end of a tubular sleeve member, the distal end of the sleevemember having a tongue member resiliently biased inward toward thecenter of the sleeve member that is configured to fit over the springmember of an exemplary bone screw retention system in its first,relaxed, position.

FIG. 10 is a partial fragmentary cross-sectional view of the screwremoval assembly of FIG. 9 showing the sleeve member having a tonguemember that is configured such that a portion of the exterior surface ofthe bone screw drive member can act against an inner surface of thetongue member to force portions of the outer surface of each of thetongue members to act against and compress the spring member of theexemplary bone screw retention system toward its second, compressedposition, wherein the distal end portion of the bone screw drive memberis configured to operatively engage a head of a bone screw.

FIG. 11 is a partial fragmentary cross-sectional view of the screwremoval assembly of FIG. 9, shown in a second position in which aportion of the exterior surface of the bone screw drive member actsagainst an inner surface of the tongue member to force portions of theouter surface of the tongue member to act against and compress thespring member of the exemplary bone screw retention system toward itssecond, compressed position, wherein the distal end portion of the bonescrew drive member is operatively engaged with the head of the bonescrew.

FIG. 12 is a partial fragmentary cross-sectional view of a screw removalassembly, showing the sleeve member having a pair of opposed tonguemember that are configured such that a portion of the exterior surfaceof the bone screw drive member acts against an inner surface of eachrespective tongue members to force portions of the outer surface of eachof the tongue members to act against and compress the spring member ofthe exemplary bone screw retention system toward its second, compressedposition, wherein the distal end portion of the bone screw drive memberis configured to operatively engage a head of a bone screw.

FIG. 13 is a side plan view of an embodiment of the bone screw removalsystem of the present invention, showing the tubular sleeve member beinginserted onto a shaft of the bone screw drive member.

FIG. 14 is an enlarged partial perspective view of the distal end of thebone screw drive member, showing an exterior surface formed at thedistal end of the bone screw drive member that is configured to engagethe tongue member of the tubular sleeve member.

FIG. 15 is a perspective view showing the screw drive member beingrotated to back out the bone screw while the distal end of the sleevemember remains in biased contact with the spring elements of the bonescrew retaining system.

DESCRIPTION OF THE INVENTION

The present invention can be understood more readily by reference to thefollowing detailed description, examples, and claims, and their previousand following description. Before the present system, devices, and/ormethods are disclosed and described, it is to be understood that thisinvention is not limited to the specific systems, devices, and/ormethods disclosed unless otherwise specified, as such can, of course,vary. It is also to be understood that the terminology used herein isfor the purpose of describing particular aspects only and is notintended to be limiting.

The following description of the invention is provided as an enablingteaching of the invention in its best, currently known embodiment. Thoseskilled in the relevant art will recognize that many changes can be madeto the embodiments described, while still obtaining the beneficialresults of the present invention. It will also be apparent that some ofthe desired benefits of the present invention can be obtained byselecting some of the features of the present invention withoututilizing other features. Accordingly, those who work in the art willrecognize that many modifications and adaptations to the presentinvention are possible and can even be desirable in certaincircumstances and are a part of the present invention. Thus, thefollowing description is provided as illustrative of the principles ofthe present invention and not in limitation thereof.

As used herein, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to a “bore” includes aspects having two or more boresunless the context clearly indicates otherwise.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect includes from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint.

As used herein, the terms “optional” or “optionally” mean that thesubsequently described event or circumstance may or may not occur, andthat the description includes instances where said event or circumstanceoccurs and instances where it does not.

In one embodiment, and referring to FIGS. 1-4A, a plate system for usewith the present invention can comprise an implant 10, particularly forthe spinal column, that can have a joining member 20 such as a plate 22that defines a plurality of openings or bores 24, bone screws 50 capableof being accommodated in the bores, and at least one spring member 70configured for releasably securing the bone screws therein the bores. Inone aspect, the spring member can come into direct contact with the bonescrew to secure the bone screw within the bores. Optionally, the springmember can form a blocking element to secure the bone screw within thebores. Further, the bone screw removal system of the present inventionprovides for the selective removal of the bone screw or screws from theplate at the physicians desire.

In one aspect, the joining member 20 comprises a plate 22 that defines aplurality of transversely extending bores 24 that are counter sunk apredetermined distance. In one exemplary aspect, a head 52 of a bonescrew 50 can be configured to be posteriorly displaceable through a bore24 of the plate from an anterior surface 26 to a posterior surface 28 ofthe plate and retained within a portion of the bore between theposterior and anterior surfaces 26, 28. In one aspect, the plate 22 canhave a generally elongated form whose outline generally departs fromrectangular due to the presences of partial lobes 30 or lateralprojections at the corners and at the center of the sides of the plate.Each partial lobe 30 has a rounded outline and, in an exemplary aspect,can define one respective bore 24. It is, of course, contemplated thatother shapes of the plate may be employed.

As noted above, the plate defines a plurality of bores 24 that extendsubstantially transverse therethrough the plate between the anterior andposterior surfaces 26, 28 of the plate and that are configured foroperable receipt of the bone screw or bone anchor. In one aspect, thebores 24 extend along a longitudinal axis from the anterior surface tothe bottom bone contacting posterior surface of the plate. In oneaspect, each bore 24 has an upper region 32 with a first diameter and alower region 34 that includes a seat 36 for the bone screw and aposteriorly extending tubular shaft 38 that extends to an opening on theposterior surface 28 of the plate 22. In one aspect, the seat 36 of thebore can have at least a partial spherical shape. In another aspect, thebores comprise a plurality of paired opposing bores

In a further aspect, the bone screw 50 has a head 52 with a maximumdiameter that is smaller than the first diameter of the upper region 32of the bore, which thereby allows the screw head to pass through thatregion of the bore. In one example, the bone screw can be a conventionalself-tapping bone screw. It is of course contemplated that conventionalnon self-tapping bones screws can be used with the system of the presentinvention. Further, it is contemplated that conventional bone screwswith at least partially rotatable heads can be used if a semi-rigidfixation procedure is desired.

In various exemplary aspects, the head 52 of each bone screw 50 cancomprise a complementary tapered section 51 that extends outwardlytherefrom the threaded shank portion 54 of the bone screw. In thisaspect, the tapered section 51 can have a tapered surface 53 thatextends from a shank 55 of the bone screw toward an upwardly facingshoulder surface 56 of the bone screw which is formed by a portion ofthe shoulder 57 of the head of the bone screw. A portion of the bonescrew above the upwardly facing shoulder surface 56 of the bone screw isconventionally configured for operative engagement with a driving tool 2and has a reduced diameter relative to the diameter of the shoulder ofthe head of the bone screw.

In one aspect, the seat 36 is configured for complementary receipt ofthe shank 55 of the bone screw 50 such that the bone screw can be fixedat a predetermined angle with respect to the plate. Alternatively, thebone screw can be fixed at an operator selective angle, i.e., beangularly displaceable. In one example, the tapered section 51 of thebone screw can be configured for complementary rotatable contact with anexemplary spherically shaped seat of the bore. It is contemplated thatthe tapered section 51 of the bone screw can be substantially linear or,optionally, substantially spherical. Further, the shank 55 of the bonescrew can be threaded in any well known fashion and may include an axialgroove to enable the bone screw to be self-boring and self-tapping.

In another aspect, the shaft 38 of the bore can have an operativediameter that is greater than the diameter of the shank 55 of the bonescrew intermediate the head of the bone screw and its distal end. As aresult, the bone screw 50 is angularly displaceable within the shaft ofthe bore between the seat and the posterior surface opening. The bonescrew can thus be tilted within the shaft 38 of the bore relative to thelongitudinal axis of the bore to facilitate positioning the bone screw50 at a desired location in the bone by advancing the threaded shankportion 54 of the bone screw within the bone at an angle relative to theposterior surface of the plate. In one aspect, the bone screw 50 can beangularly displaced relative to the longitudinal axis of the bore up toan angle α of about 20 degrees. Thus, the surgeon has, at his disposal,the freedom to orient the bone screw angularly with respect to thejoining member or plate, which allows him to optimize the anchorage. Inone aspect, the bone screws can be rotatably mounted therein theunderlying bone tissue using a conventional screw driver, a drivesocket, and the like.

In one embodiment of the present invention, the spring member 70comprises a circlip 72. In one exemplary aspect, the circlip 72 is inthe form of a circular split-ring 74 having spaced opposed ends. In oneembodiment, at least portions of one circlip is common to two bores 24in the plate 22, for example, the two bores 24 forming a pair ofopposing bores. In an alternative embodiment, at least a portion of onerespective circlip is common to one individual bore 24 of the plate 22.As used herein, the terms “circlip” and “split-ring” are usedinterchangeably without intended limitation. As described herein, it iscontemplated that the exemplified plate, bone screws and split-rings maybe supplied as part of a bone screw retaining system for use by asurgeon.

In one embodiment, the plate 22 further defines a plurality of cavities27. In one exemplary aspect, at least a portion of the cavity 27 forms atransversely extending cavity that opens on both the posterior andanterior surfaces of the plate. In another aspect, the plurality ofcavities can be spaced substantially along the longitudinal axis of theplate 22. In a further aspect, one cavity 27 is positioned therebetweeneach pair of bores 24. In this aspect, it is contemplated that thecavity can be positioned adjacent to and equidistant from each bore ofthe respective pair of bores.

In another aspect, one spring member 70, e.g., one split-ring 72, isoperable positioned therein each cavity 27 such that portions of thespring member can extend into a portion of the upper region of each ofthe bores of the paired opposing bores. In this aspect, the elasticallydeformable spring member 70 is configured to mount therein the cavity 27and is movable between a first relaxed, expanded position and a second,compressed position. In one aspect, the spring member 70 is mounted toextend outwardly substantially transverse to the longitudinal axis ofthe bore and into the upper region of the bore. As one will appreciate,in the second position, the spring member 70 has a diameter that is lessthan the diameter of the spring member when it is in the first, relaxedposition. Further, in this aspect, when the spring member 70 is in thefirst relaxed position, portions of the spring member extend overportions of the upper region 32 of each bore of the paired opposingbores, which decreases the effective inner diameter of the upper region32 of the bore. In another aspect, when the spring member 70 is in thesecond, compressed position, portions of the spring member 70 aremedially biased away from the longitudinal axis of the bore 24 towardthe diameter of the outer wall of upper region 32 of the bore. As onewill appreciate, the effective inner diameter of the upper region 32 ofthe bore is thereby increased when the spring member 70 is in the secondposition.

In one exemplified embodiment of the present invention, and as shown inFIGS. 4A-4C, the split-ring 74 is mounted therein the cavity 27 and thebone screw is inserted therein the bore of the plate (shank first intothe plate from the anterior surface of the plate) and is advancedposteriorly within the bore 24. The tapered section 51 of the head 52 ofthe bone screw engages the split-ring and applies a radially expandingforce against a peripheral surface of the split-ring to forcefully movethe split-ring medially from the first position toward the second,compressed position. One would appreciate that the interaction betweenthe split-ring 74 and the head 52 of the bone screw causes the effectiveinner diameter of the upper region 32 of the bore to increase to a sizethat allows for the posterior passage of the head of the bone screw pastthe split-ring. In this aspect, after the shoulder 57 of the head of thebone screw passes the operative plane of the spring member, thesplit-ring biases medially back to its first relaxed position such thata portion of the split-ring overlies a portion of the upwardly facingshoulder surface 56 of the head of the bone screw. Thus, when thesplit-ring 74 relaxes to its unexpanded state, it prevents the bonescrew 50 from backing out of the plate as the effective inner diameterof the upper region 32 of the bore is less than the diameter of the headof the bone screw, which effectively blocks the path that the bone screwwould have to traverse to back out or exit the bore in the plate. Withthe bone screw 50 positioned against the seat 36 of the bore, the distalthreaded portion of the bone screw is embedded in, and secured to, thebone of the patient.

In one aspect, when the head 52 of the bone screw fully engages the seat36 of the plate, the upwardly facing shoulder surface 56 of the bonescrew is located at or below the substantially transverse plane of thespring member 70. In this position, as one will appreciate, the springmember biases back toward and/or to its relaxed position because theportion of the bone screw above the plane of the spring member has areduced diameter relative to the upwardly facing surface portion of thebone screw.

In one aspect, the system of the present invention further comprises aspring mount 80 adapted to fixedly mount therein the cavity. In afurther aspect, the spring mount is configured for a compressive fitwithin the cavity 27. In another aspect, a portion of opposing sidewalls 82 of the spring mount is recessed such that the upper region ofthe bore and the recessed edge portion 84 of the spring mount define agenerally circular countersunk well 85 that is sized to receive the bonescrew. In the relaxed position, a portion of the spring member 70, 74spans across a portion of the recessed edge portion 84 and extendsoutwardly over a portion of the countersunk well substantiallytransverse to the longitudinal axis of the bore. In one aspect, thespring mount 80 has a groove 86 and/or slot defined therein the sidewalls of the spring mount, which is configured to receive a portion ofthe spring member 70 as it is medially biased toward its second,compressed position when the bone screw is being inserted therein thebore of the plate. In a further aspect, the opposed ends of the springclip can be enclosed therein the spring member.

In one embodiment, the spring member is formed from a biocompatible,flexible material such as, and not meant to be limiting, titanium alloyand the like as disclosed in U.S. Pat. Nos. 4,857,269 and 4,952,236,which are incorporated in their entirety herein by reference. Further,polymeric materials such as, for example, ultra-high molecular weightpolyethylene can also be used to form the spring member of the presentinvention.

In another aspect, the plate can define a pair of opposing openings 29.In this aspect, the pair of openings 29 is generally positioned on thelongitudinal axis of the plate. In a further aspect, each opening 29 ispositioned intermediate the center and an end of the plate. Thus, in anembodiment having bores 24 in each of the partial lobes at the cornersof the end of the plate and in the partial lobes at the center of theplate; it is contemplated that the opening can be positionedsubstantially between the respective bores. Thus, in this aspect, theplate forms a substantially open frame. These opposed openings 29 allowfor visualization of the underlying bone and tissue as the implant isbeing fixated.

In one aspect, the plate 22 may be curved to match the anatomicalcurvatures. Thus, the implant curved to best suit the anatomy andnatural curvature of the spinal column in the case of a spinalapplication. Of course, the plate 22 may be used in fracture fixation,as a tibial base plate, as a hip side plate or any application wherebone plates and screws are used. For these uses, a larger screw thanthat described herein is necessary. Thus, it is contemplated that thescrew locking system of the present invention can be scaled up or downas necessary so that any size screw can be utilized.

Referring to FIGS. 5 and 6, in another embodiment, the bone screwretention system of the plate system can comprise a spring member 70. Inthis aspect, the spring member can comprise at least one spring member100 that comprises a coil spring 102 and a piston member 104. In thisembodiment, the spring member is mounted therein a portion of the bore24 such that in a relaxed position, a portion of the piston member 104of the spring member extends over a portion of the upper region of thebore. In this aspect, a portion of the wall of the upper region of thebore defines an orifice 106 that is adapted to moveably receive the coilspring and at least a portion of the piston member therein. As oneskilled in the art will appreciate, the piston member 104 is capturedtherein the orifice 106 such that it can not be ejected from the orificeby the urging of the coil spring. Thus, the coil spring of the springmember is positioned therein a portion of the wall of the upper region32 of the bore. Of course, it is contemplated that a plurality of springmember can be mounted in each bore of the plate.

In use, upon insertion of the bone screw into the bore of the plate andits subsequent posterior movement, the tapered surface 53 of the head 52of the bone screw acts on the piston member 104 to force the pistonmember back into orifice by acting on, i.e., compressing, the underlyingcoil spring. In one aspect, when the head 52 of the bone screw fullyengages the seat 36 of the plate, the upwardly facing shoulder surfaceof the bone screw is located at or below the plane of the piston member.In this position, as one will appreciate the coil spring 102 acts on thepiston member 104 and bias the piston member outwardly toward and/or toits fully extended position.

In a further exemplary embodiment of a bone screw retention system, andas shown in FIGS. 7 and 8, the spring member 70 can be at least onearcuate spring member 110 that is mounted to a portion of the upperregion 32 of the bore such that in a relaxed position, a portion of thearcuate spring member 110 extends over a portion of the upper region ofthe bore substantially transverse to the longitudinal axis of the bore.A portion of the wall of the upper region of the bore can define agroove 112 and/or slot that is adapted to receive a portion of thearcuate spring member 70 as it is biased toward its second, compressedposition when the bone screw is being inserted therein the bore of theplate. In a further aspect, the respective ends of the arcuate springmember 110 are mounted therein a portion of the wall of the upper regionof the bore. Of course, it is contemplated that a plurality of arcuatespring members can be mounted in each bore of the plate.

Similar to the embodiment described above, in use, upon insertion of thebone screw into the bore 24 of the plate and it subsequent posterioradvancement, the tapered surface of the head of the screw 50 acts on thearcuate spring member 110 to force the arcuate spring member toward itssecond, compressed position. In one aspect, when the head of the bonescrew fully engages the seat 36 of the plate, the upwardly facingsurface of the bone screw is located at or below the plane of the springmember 70. In this position, as one will appreciate, the arcuate springmember 110 biases toward and/or to its relaxed position because theportion of the bone screw above the plane of the spring member has areduced diameter relative to the upwardly facing shoulder surfaceportion of the bone screw.

An exemplary embodiment of the bone screw removal system of the presentinvention is shown in FIGS. 9-15. In one embodiment, a bone screwremoval assembly 230 is shown that comprises an elongated bone screwdrive member 240 and a tubular sleeve member 250. In one aspect, thescrew drive member has a distal end 242 that is configured tooperatively engage the head 52 of a bone screw. In another aspect, thesleeve member 250 is configured to move longitudinally relative to andabout the elongate bone screw drive member. Of course, it iscontemplated that that the sleeve member can be slidabley mountedthereto the bone screw drive member.

In one embodiment, the sleeve member 250 has at least one tongue member260 formed in a portion of the distal end 252 of the sleeve member. Inone exemplary aspect, each tongue member 260, in a first position, isbent or hinged inwardly toward the longitudinal center axis of conduit261 of the sleeve member that extends from the distal end 252 to theproximal end 253 of the sleeve member 250. In one aspect, the conduit ofthe sleeve member has a first diameter. In a further aspect, the firstaspect of the conduit of the sleeve member is greater than the diameterof the head of the bone screw.

In another aspect, each tongue member 260 is configured to beresiliently biased toward the peripheral wall portions 257 of the distalend of the sleeve member, i.e., toward an operative position, ifsufficient force is applied to an inner surface 262 of the tonguemember. In the first position, the at least one tongue member defines atleast one slot 258 in the peripheral wall of the distal end 252 of thesleeve member. In one aspect, each slot 258 has a width that is greaterthan the width of the spring member 70 in its first, relaxed position.

In various exemplary aspects, the at least one tongue member comprises apair of tongue members or a plurality of tongue members. In anotheraspect, the at least one tongue member equals the number of springmembers of the bone screw retaining system. It is of course contemplatedthat other designs of the tongue member can be as long as it isresiliently urged to bias as described herein.

In use, the sleeve member 250 is placed into a seated position withinthe bore of the plate such that each respective slot 258 of the sleevemember overlies one respective spring member 70. Thus, each tonguemember 260 would be positioned adjacent or in opposition to a springmember 70. The bone screw drive member 240 has an exterior surface 245that is configured to contact at least a portion of the inner surface262 of the tongue member such that, as the screw drive member is pusheddown into engagement with the head of the bone screw, the exteriorsurface 245 of the screw drive member 240 acts against the resistance ofthe tongue member 260 to bias/rotate the tongue member outward towardthe peripheral wall 257 of the sleeve member. In this aspect, at least aportion of the exterior surface of the bone screw drive member proximatethe distal end of the bone screw member has a diameter that issubstantially the same as the first diameter of the sleeve member and isconfigured for slideable receipt therein the conduit of the sleevemember.

One would appreciate that, as the tongue member 260 is biased outwardly,the spring member 70, being acted on by the outer surface 264 of thetongue member, moves to its second compressed position. Thereupon, theindependent rotation of the screw drive member 240 relative to thesleeve member 250 allows for the removal of the bone screw. When thesleeve member is removed from the bore, the spring member is allowed tobias back to its first relaxed position.

In use, the at least one tongue member is movable about and between afirst, relaxed position, and a second, operative position. In the firstposition, the tongue member is resiliently biased inward toward thecenter of the conduit 255 of the sleeve member, and, in the secondposition, the at least a portion of the exterior surface of the bonescrew drive member proximate the distal end of the bone screw drivemember acts against an inner surface of the at least one tongue memberto urge the at least one tongue member outwardly away from the center ofthe conduit of the sleeve member. The subsequent rotation of the bonescrew drive member backs moves both the bone screw and the bone screwdrive member in an anterior direction such that the spring member biasesback to contact with the tapered portion of the screw as it isanteriorly moved.

In another embodiment, the upper region of the formed bores 24 in theplate 22 have a diameter that is greater than the diameter of theshoulder 57 of the bone screw 50 such that a predetermined spaced isformed between the shoulder of the bone screw and the wall of the upperregion 36 of the bore when the bone screw is positioned on the seat ofthe bore. In this embodiment, the tubular sleeve member is adapted toseat therein the predetermined space such that the removal of the bonescrew is not obstructed. In another aspect, the bone screw drive membercan be rotated independently of the sleeve member until the bone screwis removed.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope or spirit of the invention. Otherembodiments of the invention will be apparent to those skilled in theart from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only.

1. A bone screw removal system for removing bone screws from a platethat defines a plurality of transversely extending bores and a pluralityof cavities and a bone screw retaining system that includes anelastically deformable spring member positioned therein each cavity suchthat portions of the spring member can extend into a portion of theupper region of each of the bores, wherein the spring member isconfigured to mount therein the cavity and is movable between a firstrelaxed position and a second compressed position, wherein, in the firstrelaxed position, at least a portion of the spring member extendsoutwardly substantially transverse to the longitudinal axis of the boreand into the upper region of the bore, wherein, in the first relaxedposition, portions of the spring member extend over portions of theupper region of each bore of the pair of opposing bores, which decreasesthe effective inner diameter of the upper region of the bore, andwherein, in the second compressed position, portions of the springmember are medially biased away from the longitudinal axis of the boretoward the outer wall of upper region of the bore, which increases theeffective inner diameter of the upper region of the bore, the bone screwremoval system comprising: a tubular sleeve member having at least onetongue member formed in a distal end of the sleeve member and defining aconduit extending from the distal end to a proximal end of the sleevemember, wherein the at least one tongue member is resiliently biasedinward toward a center of the conduit of the sleeve member, and whereinthe conduit of the sleeve member has a first diameter; and a bone screwdrive member having a distal end and a proximal end, wherein at least aportion of an exterior surface of the bone screw drive member proximatethe distal end of the bone screw drive member has a diameter that issubstantially the same as the first diameter of the sleeve member and isconfigured for slideably receipt therein the conduit of the sleevemember, wherein the at least one tongue member is movable about andbetween a first, relaxed position, in which the tongue member isresiliently biased inward toward the center of the conduit of the sleevemember, and a second position, in which the at least a portion of theexterior surface of the bone screw drive member proximate the distal endof the bone screw drive member acts against an inner surface of the atleast one tongue member to urge the at least one tongue member outwardlyaway from the center of the conduit of the sleeve member.
 2. The bonescrew removal system of claim 1, wherein the at least one tongue membercomprises a pair of tongue members.
 3. The bone screw removal system ofclaim 1, wherein the at least one tongue member comprises a plurality oftongue members.
 4. The bone screw removal system of claim 1, wherein theat least one tongue member is equal to the number of spring members ofthe bone screw retaining system.
 5. The bone screw removal system ofclaim 1, wherein a portion of the distal end of the bone screw driver isconfigured to operatively engage a head of the bone screw.
 6. The bonescrew removal system of claim 5, wherein a portion of the distal end ofthe bone screw driver is configured to seat therein a bore of the plate,and wherein the at least one tongue member is positioned in oppositionto the spring member.
 7. The bone screw removal system of claim 6,wherein the first diameter of the conduit of the sleeve member isgreater than the diameter of the head of the bone screw.
 8. The bonescrew removal system of claim 1, wherein a portion of the proximal endof the bone screw drive member forms a handle.
 9. The bone screw removalsystem of claim 1, wherein the conduit of the sleeve member is slideablymountable to bone screw drive member such that the sleeve member can bemoved axially about a longitudinal axis of the bone screw drive member.10. A bone screw removal system for removing bone screws from a platethat defines a plurality of transversely extending bores and a pluralityof cavities and a bone screw retaining system that includes anelastically deformable spring member positioned therein each cavity suchthat portions of the spring member can extend into a portion of theupper region of each of the bores, wherein the spring member isconfigured to mount therein the cavity and is movable between a firstrelaxed position and a second compressed position, wherein, in the firstrelaxed position, at least a portion of the spring member extendsoutwardly substantially transverse to the longitudinal axis of the boreand into the upper region of the bore, wherein, in the first relaxedposition, portions of the spring member extend over portions of theupper region of each bore of the pair of opposing bores, which decreasesthe effective inner diameter of the upper region of the bore, andwherein, in the second compressed position, portions of the springmember are medially biased away from the longitudinal axis of the boretoward the outer wall of upper region of the bore, which increases theeffective inner diameter of the upper region of the bore, the bone screwremoval system comprising: a tubular sleeve member having at least onetongue member formed in a distal end of the sleeve member and defining aconduit extending from the distal end to a proximal end of the sleevemember, wherein the at least one tongue member is resiliently biasedinward toward a center of the conduit of the sleeve member; and a bonescrew drive member having a distal end and a proximal end, wherein atleast a portion of an exterior surface of the bone screw drive memberproximate the distal end of the bone screw drive member is configuredfor slideably receipt therein the conduit of the sleeve member, whereinthe at least one tongue member is movable about and between a first,relaxed position, in which the tongue member is resiliently biasedinward toward the center of the conduit of the sleeve member, and asecond position, in which the at least a portion of the exterior surfaceof the bone screw drive member proximate the distal end of the bonescrew drive member acts against an inner surface of the at least onetongue member to urge the at least one tongue member outwardly away fromthe center of the conduit of the sleeve member and toward a peripheraledge of the distal end of the sleeve member.
 11. The bone screw removalsystem of claim 10, wherein the conduit of the sleeve member has a firstdiameter, and wherein the exterior surface of the bone screw drivemember proximate the distal end of the bone screw drive member has adiameter that is substantially the same as the first diameter of thesleeve member.
 12. The bone screw removal system of claim 10, whereinthe at least one tongue member comprises a pair of tongue members. 13.The bone screw removal system of claim 10, wherein the at least onetongue member comprises a plurality of tongue members.
 14. The bonescrew removal system of claim 10, wherein the at least one tongue memberis equal to the number of spring members of the bone screw retainingsystem.
 15. The bone screw removal system of claim 10, wherein a portionof the distal end of the bone screw driver is configured to operativelyengage a head of the bone screw.
 16. The bone screw removal system ofclaim 15, wherein a portion of the distal end of the bone screw driveris configured to seat therein a bore of the plate, and wherein the atleast one tongue member is positioned in opposition to the springmember.
 17. The bone screw removal system of claim 16, wherein the firstdiameter of the conduit of the sleeve member is greater than thediameter of the head of the bone screw.
 18. The bone screw removalsystem of claim 10, wherein a portion of the proximal end of the bonescrew drive member forms a handle.
 19. The bone screw removal system ofclaim 10, wherein the conduit of the sleeve member is slideablymountable to bone screw drive member such that the sleeve member can bemoved axially about a longitudinal axis of the bone screw drive member.